There have been data storage devices that convert (A/D converts) an externally supplied analog signal, such as an audio signal or an image signal into digital data, store the digital data into a semiconductor memory, such as a RAM, read the data from the RAM as the need arises, decides (D/A converts) it, and output the decoded data, as disclosed in U.S. Pat. No. 4,368,988.
With conventional data storage devices, when a single semiconductor memory is used as an audio data recording and reproducing device for a single audio data item or an image data storage device for a single image (e.g., a single TV screen of image data), addressing is initiated, starting at the first address in the semiconductor memory in recording or reproducing audio data or in storing or reading image data. However, in a case where a single semiconductor memory is divided into blocks and the blocks are selectively recorded into or reproduced from image data is stored into the individual blocks, one image for one block, addressing must be initiated, starting at the head address of the selected block. To do this, it is necessary to send data on the head address of the selected block to the address control section, preset it, and update the addresses, starting at the head address.
When the encoded data is stored in a volatile memory, such as a RAM, the stored contents will disappear in the case of the expiration of the battery's service life, the replacement of the battery, or a power failure. To avoid the loss of the stored data, use of a nonvolatile memory, such as an EEPROM, can be considered. Such a nonvolatile memory, however, requires a very high driving voltage, as compared with a CMOS circuit that operates on about 1V, for example. For this reason, an electronic circuit for controlling recording and reproducing operations or image data storing and reading operations that operates on a relatively low voltage and an electronic circuit including nonvolatile memories have to be composed of separate chips, which need to be controlled by different voltages separately. As described above, when the main circuit section and the electronic circuit including nonvolatile memories are composed of separate chips and a single nonvolatile memory is divided into blocks as described earlier, and the blocks are selectively recorded into and reproduced from, the head address of each block must be addressed directly, with the result that a plurality of terminals are needed as the input terminals for address data, which leads to the problem that the size of the electronic circuit chip including nonvolatile memories becomes large.